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  182.   <section id="module-array">

  183. <span id="array-efficient-arrays-of-numeric-values"></span><h1><a class="reference internal" href="#module-array" title="array: Space efficient arrays of uniformly typed numeric values."><code class="xref py py-mod docutils literal notranslate"><span class="pre">array</span></code></a> — Efficient arrays of numeric values<a class="headerlink" href="#module-array" title="Link to this heading">¶</a></h1>

  184. <hr class="docutils" id="index-0" />

  185. <p>This module defines an object type which can compactly represent an array of

  186. basic values: characters, integers, floating point numbers.  Arrays are sequence

  187. types and behave very much like lists, except that the type of objects stored in

  188. them is constrained.  The type is specified at object creation time by using a

  189. <em class="dfn">type code</em>, which is a single character.  The following type codes are

  190. defined:</p>

  191. <table class="docutils align-default">

  192. <thead>

  193. <tr class="row-odd"><th class="head"><p>Type code</p></th>

  194. <th class="head"><p>C Type</p></th>

  195. <th class="head"><p>Python Type</p></th>

  196. <th class="head"><p>Minimum size in bytes</p></th>

  197. <th class="head"><p>Notes</p></th>

  198. </tr>

  199. </thead>

  200. <tbody>

  201. <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'b'</span></code></p></td>

  202. <td><p>signed char</p></td>

  203. <td><p>int</p></td>

  204. <td><p>1</p></td>

  205. <td></td>

  206. </tr>

  207. <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'B'</span></code></p></td>

  208. <td><p>unsigned char</p></td>

  209. <td><p>int</p></td>

  210. <td><p>1</p></td>

  211. <td></td>

  212. </tr>

  213. <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'u'</span></code></p></td>

  214. <td><p>wchar_t</p></td>

  215. <td><p>Unicode character</p></td>

  216. <td><p>2</p></td>

  217. <td><p>(1)</p></td>

  218. </tr>

  219. <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'h'</span></code></p></td>

  220. <td><p>signed short</p></td>

  221. <td><p>int</p></td>

  222. <td><p>2</p></td>

  223. <td></td>

  224. </tr>

  225. <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'H'</span></code></p></td>

  226. <td><p>unsigned short</p></td>

  227. <td><p>int</p></td>

  228. <td><p>2</p></td>

  229. <td></td>

  230. </tr>

  231. <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'i'</span></code></p></td>

  232. <td><p>signed int</p></td>

  233. <td><p>int</p></td>

  234. <td><p>2</p></td>

  235. <td></td>

  236. </tr>

  237. <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'I'</span></code></p></td>

  238. <td><p>unsigned int</p></td>

  239. <td><p>int</p></td>

  240. <td><p>2</p></td>

  241. <td></td>

  242. </tr>

  243. <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'l'</span></code></p></td>

  244. <td><p>signed long</p></td>

  245. <td><p>int</p></td>

  246. <td><p>4</p></td>

  247. <td></td>

  248. </tr>

  249. <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'L'</span></code></p></td>

  250. <td><p>unsigned long</p></td>

  251. <td><p>int</p></td>

  252. <td><p>4</p></td>

  253. <td></td>

  254. </tr>

  255. <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'q'</span></code></p></td>

  256. <td><p>signed long long</p></td>

  257. <td><p>int</p></td>

  258. <td><p>8</p></td>

  259. <td></td>

  260. </tr>

  261. <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'Q'</span></code></p></td>

  262. <td><p>unsigned long long</p></td>

  263. <td><p>int</p></td>

  264. <td><p>8</p></td>

  265. <td></td>

  266. </tr>

  267. <tr class="row-odd"><td><p><code class="docutils literal notranslate"><span class="pre">'f'</span></code></p></td>

  268. <td><p>float</p></td>

  269. <td><p>float</p></td>

  270. <td><p>4</p></td>

  271. <td></td>

  272. </tr>

  273. <tr class="row-even"><td><p><code class="docutils literal notranslate"><span class="pre">'d'</span></code></p></td>

  274. <td><p>double</p></td>

  275. <td><p>float</p></td>

  276. <td><p>8</p></td>

  277. <td></td>

  278. </tr>

  279. </tbody>

  280. </table>

  281. <p>Notes:</p>

  282. <ol class="arabic">

  283. <li><p>It can be 16 bits or 32 bits depending on the platform.</p>

  284. <div class="versionchanged">

  285. <p><span class="versionmodified changed">Changed in version 3.9: </span><code class="docutils literal notranslate"><span class="pre">array('u')</span></code> now uses <code class="xref c c-type docutils literal notranslate"><span class="pre">wchar_t</span></code> as C type instead of deprecated

  286. <code class="docutils literal notranslate"><span class="pre">Py_UNICODE</span></code>. This change doesn’t affect its behavior because

  287. <code class="docutils literal notranslate"><span class="pre">Py_UNICODE</span></code> is alias of <code class="xref c c-type docutils literal notranslate"><span class="pre">wchar_t</span></code> since Python 3.3.</p>

  288. </div>

  289. <div class="deprecated-removed">

  290. <p><span class="versionmodified">Deprecated since version 3.3, will be removed in version 4.0.</span></p>

  291. </div>

  292. </li>

  293. </ol>

  294. <p>The actual representation of values is determined by the machine architecture

  295. (strictly speaking, by the C implementation).  The actual size can be accessed

  296. through the <a class="reference internal" href="#array.array.itemsize" title="array.array.itemsize"><code class="xref py py-attr docutils literal notranslate"><span class="pre">array.itemsize</span></code></a> attribute.</p>

  297. <p>The module defines the following item:</p>

  298. <dl class="py data">

  299. <dt class="sig sig-object py" id="array.typecodes">

  300. <span class="sig-prename descclassname"><span class="pre">array.</span></span><span class="sig-name descname"><span class="pre">typecodes</span></span><a class="headerlink" href="#array.typecodes" title="Link to this definition">¶</a></dt>

  301. <dd><p>A string with all available type codes.</p>

  302. </dd></dl>

  303. 

  304. <p>The module defines the following type:</p>

  305. <dl class="py class">

  306. <dt class="sig sig-object py" id="array.array">

  307. <em class="property"><span class="pre">class</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">array.</span></span><span class="sig-name descname"><span class="pre">array</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">typecode</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">initializer</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array" title="Link to this definition">¶</a></dt>

  308. <dd><p>A new array whose items are restricted by <em>typecode</em>, and initialized

  309. from the optional <em>initializer</em> value, which must be a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a>

  310. or <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> object, a Unicode string, or iterable over elements

  311. of the appropriate type.</p>

  312. <p>If given a <a class="reference internal" href="stdtypes.html#bytes" title="bytes"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytes</span></code></a> or <a class="reference internal" href="stdtypes.html#bytearray" title="bytearray"><code class="xref py py-class docutils literal notranslate"><span class="pre">bytearray</span></code></a> object, the initializer

  313. is passed to the new array’s <a class="reference internal" href="#array.array.frombytes" title="array.array.frombytes"><code class="xref py py-meth docutils literal notranslate"><span class="pre">frombytes()</span></code></a> method;

  314. if given a Unicode string, the initializer is passed to the

  315. <a class="reference internal" href="#array.array.fromunicode" title="array.array.fromunicode"><code class="xref py py-meth docutils literal notranslate"><span class="pre">fromunicode()</span></code></a> method;

  316. otherwise, the initializer’s iterator is passed to the <a class="reference internal" href="#array.array.extend" title="array.array.extend"><code class="xref py py-meth docutils literal notranslate"><span class="pre">extend()</span></code></a> method

  317. to add initial items to the array.</p>

  318. <p>Array objects support the ordinary sequence operations of indexing, slicing,

  319. concatenation, and multiplication.  When using slice assignment, the assigned

  320. value must be an array object with the same type code; in all other cases,

  321. <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> is raised. Array objects also implement the buffer interface,

  322. and may be used wherever <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like objects</span></a> are supported.</p>

  323. <p class="audit-hook">Raises an <a class="reference internal" href="sys.html#auditing"><span class="std std-ref">auditing event</span></a> <code class="docutils literal notranslate"><span class="pre">array.__new__</span></code> with arguments <code class="docutils literal notranslate"><span class="pre">typecode</span></code>, <code class="docutils literal notranslate"><span class="pre">initializer</span></code>.</p>

  324. <dl class="py attribute">

  325. <dt class="sig sig-object py" id="array.array.typecode">

  326. <span class="sig-name descname"><span class="pre">typecode</span></span><a class="headerlink" href="#array.array.typecode" title="Link to this definition">¶</a></dt>

  327. <dd><p>The typecode character used to create the array.</p>

  328. </dd></dl>

  329. 

  330. <dl class="py attribute">

  331. <dt class="sig sig-object py" id="array.array.itemsize">

  332. <span class="sig-name descname"><span class="pre">itemsize</span></span><a class="headerlink" href="#array.array.itemsize" title="Link to this definition">¶</a></dt>

  333. <dd><p>The length in bytes of one array item in the internal representation.</p>

  334. </dd></dl>

  335. 

  336. <dl class="py method">

  337. <dt class="sig sig-object py" id="array.array.append">

  338. <span class="sig-name descname"><span class="pre">append</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">x</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.append" title="Link to this definition">¶</a></dt>

  339. <dd><p>Append a new item with value <em>x</em> to the end of the array.</p>

  340. </dd></dl>

  341. 

  342. <dl class="py method">

  343. <dt class="sig sig-object py" id="array.array.buffer_info">

  344. <span class="sig-name descname"><span class="pre">buffer_info</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.buffer_info" title="Link to this definition">¶</a></dt>

  345. <dd><p>Return a tuple <code class="docutils literal notranslate"><span class="pre">(address,</span> <span class="pre">length)</span></code> giving the current memory address and the

  346. length in elements of the buffer used to hold array’s contents.  The size of the

  347. memory buffer in bytes can be computed as <code class="docutils literal notranslate"><span class="pre">array.buffer_info()[1]</span> <span class="pre">*</span>

  348. <span class="pre">array.itemsize</span></code>.  This is occasionally useful when working with low-level (and

  349. inherently unsafe) I/O interfaces that require memory addresses, such as certain

  350. <code class="xref c c-func docutils literal notranslate"><span class="pre">ioctl()</span></code> operations.  The returned numbers are valid as long as the array

  351. exists and no length-changing operations are applied to it.</p>

  352. <div class="admonition note">

  353. <p class="admonition-title">Note</p>

  354. <p>When using array objects from code written in C or C++ (the only way to

  355. effectively make use of this information), it makes more sense to use the buffer

  356. interface supported by array objects.  This method is maintained for backward

  357. compatibility and should be avoided in new code.  The buffer interface is

  358. documented in <a class="reference internal" href="../c-api/buffer.html#bufferobjects"><span class="std std-ref">Buffer Protocol</span></a>.</p>

  359. </div>

  360. </dd></dl>

  361. 

  362. <dl class="py method">

  363. <dt class="sig sig-object py" id="array.array.byteswap">

  364. <span class="sig-name descname"><span class="pre">byteswap</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.byteswap" title="Link to this definition">¶</a></dt>

  365. <dd><p>“Byteswap” all items of the array.  This is only supported for values which are

  366. 1, 2, 4, or 8 bytes in size; for other types of values, <a class="reference internal" href="exceptions.html#RuntimeError" title="RuntimeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">RuntimeError</span></code></a> is

  367. raised.  It is useful when reading data from a file written on a machine with a

  368. different byte order.</p>

  369. </dd></dl>

  370. 

  371. <dl class="py method">

  372. <dt class="sig sig-object py" id="array.array.count">

  373. <span class="sig-name descname"><span class="pre">count</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">x</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.count" title="Link to this definition">¶</a></dt>

  374. <dd><p>Return the number of occurrences of <em>x</em> in the array.</p>

  375. </dd></dl>

  376. 

  377. <dl class="py method">

  378. <dt class="sig sig-object py" id="array.array.extend">

  379. <span class="sig-name descname"><span class="pre">extend</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">iterable</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.extend" title="Link to this definition">¶</a></dt>

  380. <dd><p>Append items from <em>iterable</em> to the end of the array.  If <em>iterable</em> is another

  381. array, it must have <em>exactly</em> the same type code; if not, <a class="reference internal" href="exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a> will

  382. be raised.  If <em>iterable</em> is not an array, it must be iterable and its elements

  383. must be the right type to be appended to the array.</p>

  384. </dd></dl>

  385. 

  386. <dl class="py method">

  387. <dt class="sig sig-object py" id="array.array.frombytes">

  388. <span class="sig-name descname"><span class="pre">frombytes</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">buffer</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.frombytes" title="Link to this definition">¶</a></dt>

  389. <dd><p>Appends items from the <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a>, interpreting

  390. its content as an array of machine values (as if it had been read

  391. from a file using the <a class="reference internal" href="#array.array.fromfile" title="array.array.fromfile"><code class="xref py py-meth docutils literal notranslate"><span class="pre">fromfile()</span></code></a> method).</p>

  392. <div class="versionadded">

  393. <p><span class="versionmodified added">New in version 3.2: </span><code class="xref py py-meth docutils literal notranslate"><span class="pre">fromstring()</span></code> is renamed to <a class="reference internal" href="#array.array.frombytes" title="array.array.frombytes"><code class="xref py py-meth docutils literal notranslate"><span class="pre">frombytes()</span></code></a> for clarity.</p>

  394. </div>

  395. </dd></dl>

  396. 

  397. <dl class="py method">

  398. <dt class="sig sig-object py" id="array.array.fromfile">

  399. <span class="sig-name descname"><span class="pre">fromfile</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">f</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">n</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.fromfile" title="Link to this definition">¶</a></dt>

  400. <dd><p>Read <em>n</em> items (as machine values) from the <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file object</span></a> <em>f</em> and append

  401. them to the end of the array.  If less than <em>n</em> items are available,

  402. <a class="reference internal" href="exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a> is raised, but the items that were available are still

  403. inserted into the array.</p>

  404. </dd></dl>

  405. 

  406. <dl class="py method">

  407. <dt class="sig sig-object py" id="array.array.fromlist">

  408. <span class="sig-name descname"><span class="pre">fromlist</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">list</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.fromlist" title="Link to this definition">¶</a></dt>

  409. <dd><p>Append items from the list.  This is equivalent to <code class="docutils literal notranslate"><span class="pre">for</span> <span class="pre">x</span> <span class="pre">in</span> <span class="pre">list:</span>

  410. <span class="pre">a.append(x)</span></code> except that if there is a type error, the array is unchanged.</p>

  411. </dd></dl>

  412. 

  413. <dl class="py method">

  414. <dt class="sig sig-object py" id="array.array.fromunicode">

  415. <span class="sig-name descname"><span class="pre">fromunicode</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">s</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.fromunicode" title="Link to this definition">¶</a></dt>

  416. <dd><p>Extends this array with data from the given Unicode string.

  417. The array must have type code <code class="docutils literal notranslate"><span class="pre">'u'</span></code>; otherwise a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> is raised.

  418. Use <code class="docutils literal notranslate"><span class="pre">array.frombytes(unicodestring.encode(enc))</span></code> to append Unicode data to an

  419. array of some other type.</p>

  420. </dd></dl>

  421. 

  422. <dl class="py method">

  423. <dt class="sig sig-object py" id="array.array.index">

  424. <span class="sig-name descname"><span class="pre">index</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">x</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">start</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">stop</span></span></em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.index" title="Link to this definition">¶</a></dt>

  425. <dd><p>Return the smallest <em>i</em> such that <em>i</em> is the index of the first occurrence of

  426. <em>x</em> in the array.  The optional arguments <em>start</em> and <em>stop</em> can be

  427. specified to search for <em>x</em> within a subsection of the array.  Raise

  428. <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> if <em>x</em> is not found.</p>

  429. <div class="versionchanged">

  430. <p><span class="versionmodified changed">Changed in version 3.10: </span>Added optional <em>start</em> and <em>stop</em> parameters.</p>

  431. </div>

  432. </dd></dl>

  433. 

  434. <dl class="py method">

  435. <dt class="sig sig-object py" id="array.array.insert">

  436. <span class="sig-name descname"><span class="pre">insert</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">i</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">x</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.insert" title="Link to this definition">¶</a></dt>

  437. <dd><p>Insert a new item with value <em>x</em> in the array before position <em>i</em>. Negative

  438. values are treated as being relative to the end of the array.</p>

  439. </dd></dl>

  440. 

  441. <dl class="py method">

  442. <dt class="sig sig-object py" id="array.array.pop">

  443. <span class="sig-name descname"><span class="pre">pop</span></span><span class="sig-paren">(</span><span class="optional">[</span><em class="sig-param"><span class="n"><span class="pre">i</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.pop" title="Link to this definition">¶</a></dt>

  444. <dd><p>Removes the item with the index <em>i</em> from the array and returns it. The optional

  445. argument defaults to <code class="docutils literal notranslate"><span class="pre">-1</span></code>, so that by default the last item is removed and

  446. returned.</p>

  447. </dd></dl>

  448. 

  449. <dl class="py method">

  450. <dt class="sig sig-object py" id="array.array.remove">

  451. <span class="sig-name descname"><span class="pre">remove</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">x</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.remove" title="Link to this definition">¶</a></dt>

  452. <dd><p>Remove the first occurrence of <em>x</em> from the array.</p>

  453. </dd></dl>

  454. 

  455. <dl class="py method">

  456. <dt class="sig sig-object py" id="array.array.reverse">

  457. <span class="sig-name descname"><span class="pre">reverse</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.reverse" title="Link to this definition">¶</a></dt>

  458. <dd><p>Reverse the order of the items in the array.</p>

  459. </dd></dl>

  460. 

  461. <dl class="py method">

  462. <dt class="sig sig-object py" id="array.array.tobytes">

  463. <span class="sig-name descname"><span class="pre">tobytes</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.tobytes" title="Link to this definition">¶</a></dt>

  464. <dd><p>Convert the array to an array of machine values and return the bytes

  465. representation (the same sequence of bytes that would be written to a file by

  466. the <a class="reference internal" href="#array.array.tofile" title="array.array.tofile"><code class="xref py py-meth docutils literal notranslate"><span class="pre">tofile()</span></code></a> method.)</p>

  467. <div class="versionadded">

  468. <p><span class="versionmodified added">New in version 3.2: </span><code class="xref py py-meth docutils literal notranslate"><span class="pre">tostring()</span></code> is renamed to <a class="reference internal" href="#array.array.tobytes" title="array.array.tobytes"><code class="xref py py-meth docutils literal notranslate"><span class="pre">tobytes()</span></code></a> for clarity.</p>

  469. </div>

  470. </dd></dl>

  471. 

  472. <dl class="py method">

  473. <dt class="sig sig-object py" id="array.array.tofile">

  474. <span class="sig-name descname"><span class="pre">tofile</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">f</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#array.array.tofile" title="Link to this definition">¶</a></dt>

  475. <dd><p>Write all items (as machine values) to the <a class="reference internal" href="../glossary.html#term-file-object"><span class="xref std std-term">file object</span></a> <em>f</em>.</p>

  476. </dd></dl>

  477. 

  478. <dl class="py method">

  479. <dt class="sig sig-object py" id="array.array.tolist">

  480. <span class="sig-name descname"><span class="pre">tolist</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.tolist" title="Link to this definition">¶</a></dt>

  481. <dd><p>Convert the array to an ordinary list with the same items.</p>

  482. </dd></dl>

  483. 

  484. <dl class="py method">

  485. <dt class="sig sig-object py" id="array.array.tounicode">

  486. <span class="sig-name descname"><span class="pre">tounicode</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#array.array.tounicode" title="Link to this definition">¶</a></dt>

  487. <dd><p>Convert the array to a Unicode string.  The array must have a type <code class="docutils literal notranslate"><span class="pre">'u'</span></code>;

  488. otherwise a <a class="reference internal" href="exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> is raised. Use <code class="docutils literal notranslate"><span class="pre">array.tobytes().decode(enc)</span></code> to

  489. obtain a Unicode string from an array of some other type.</p>

  490. </dd></dl>

  491. 

  492. </dd></dl>

  493. 

  494. <p>The string representation of array objects has the form

  495. <code class="docutils literal notranslate"><span class="pre">array(typecode,</span> <span class="pre">initializer)</span></code>.

  496. The <em>initializer</em> is omitted if the array is empty, otherwise it is

  497. a Unicode string if the <em>typecode</em> is <code class="docutils literal notranslate"><span class="pre">'u'</span></code>, otherwise it is

  498. a list of numbers.

  499. The string representation is guaranteed to be able to be converted back to an

  500. array with the same type and value using <a class="reference internal" href="functions.html#eval" title="eval"><code class="xref py py-func docutils literal notranslate"><span class="pre">eval()</span></code></a>, so long as the

  501. <a class="reference internal" href="#array.array" title="array.array"><code class="xref py py-class docutils literal notranslate"><span class="pre">array</span></code></a> class has been imported using <code class="docutils literal notranslate"><span class="pre">from</span> <span class="pre">array</span> <span class="pre">import</span> <span class="pre">array</span></code>.

  502. Variables <code class="docutils literal notranslate"><span class="pre">inf</span></code> and <code class="docutils literal notranslate"><span class="pre">nan</span></code> must also be defined if it contains

  503. corresponding floating point values.

  504. Examples:</p>

  505. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">array</span><span class="p">(</span><span class="s1">&#39;l&#39;</span><span class="p">)</span>

  506. <span class="n">array</span><span class="p">(</span><span class="s1">&#39;u&#39;</span><span class="p">,</span> <span class="s1">&#39;hello </span><span class="se">\u2641</span><span class="s1">&#39;</span><span class="p">)</span>

  507. <span class="n">array</span><span class="p">(</span><span class="s1">&#39;l&#39;</span><span class="p">,</span> <span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">5</span><span class="p">])</span>

  508. <span class="n">array</span><span class="p">(</span><span class="s1">&#39;d&#39;</span><span class="p">,</span> <span class="p">[</span><span class="mf">1.0</span><span class="p">,</span> <span class="mf">2.0</span><span class="p">,</span> <span class="mf">3.14</span><span class="p">,</span> <span class="o">-</span><span class="n">inf</span><span class="p">,</span> <span class="n">nan</span><span class="p">])</span>

  509. </pre></div>

  510. </div>

  511. <div class="admonition seealso">

  512. <p class="admonition-title">See also</p>

  513. <dl class="simple">

  514. <dt>Module <a class="reference internal" href="struct.html#module-struct" title="struct: Interpret bytes as packed binary data."><code class="xref py py-mod docutils literal notranslate"><span class="pre">struct</span></code></a></dt><dd><p>Packing and unpacking of heterogeneous binary data.</p>

  515. </dd>

  516. <dt>Module <a class="reference internal" href="xdrlib.html#module-xdrlib" title="xdrlib: Encoders and decoders for the External Data Representation (XDR). (deprecated)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">xdrlib</span></code></a></dt><dd><p>Packing and unpacking of External Data Representation (XDR) data as used in some

  517. remote procedure call systems.</p>

  518. </dd>

  519. <dt><a class="reference external" href="https://numpy.org/">NumPy</a></dt><dd><p>The NumPy package defines another array type.</p>

  520. </dd>

  521. </dl>

  522. </div>

  523. </section>

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